The present invention relates to a die, and more particularly to a die for continuously extruding hollow articles, such as pipe, from thermosetting resins.
Pipes made of thermosetting resins have been previously used only within a relatively narrow field notwithstanding their superior properties. The reasons for this primarily pertain to the absence of suitable shaping apparatuses at the present time, and the relatively late development of uses for these resins. However, owing to the recent development of their uses it has become increasing important to devise apparatuses for extruding hollow articles from thermosetting resins at a relatively low cost.
Although the process of continually extruding pipe from thermoplastic resins had been know, it was very difficult to continuously extrude pipes, etc. from thermosetting resins due to their specific properties. Thermosetting resins become self-heated during the process of continuous extrusion through a die whose temperature is above their setting temperature so that a premature curing of the resins occurs at a deep point within the die and further extrusion is prevented.
Thus, the continuous extrusion of hollow articles, such as pipe, from thermosetting resins could only be carried out at a relatively low speed, and their costs were necessarily high.